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| Temporal variation of the coarse sediment yield in the Wudinghe River Basin and the cause of formation |
| Xu Jiongxin |
Institute of Geographical Sciences and Natural Resources Research,Chinese Academy of Sciences,Key Laboratory of Water Cycle and Related
Land Surface Processes,Chinese Academy of Sciences,100101,Beijing,China |
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Abstract Based on the data of suspended sediment yield,suspended sediment grain size,precipitation,sand-dust storms and areas of soil and water conservation measures,a study has been made on the relatively coarse(>0.05 mm) sediment yield(Qs,>0.05) in the Wudinghe River.The Qs,>0.05 shows a decreasing trend,which can be related with the decrease in annual precipitation(Pm) and number of sand-dust storm days(Pss) and the increased area of soil and water conservation measures(Atfgc).To assess the influence of precipitation and sand-dust storm on Qs,>0.05,a number of two-variable regression equations has been established,which Qs,>0.05 relates to Pss and one of the four rainfall indices: annualprecipitation(Pm),high-flow season(June-September)(P6-9),annually 1 day maximum(P1) and maximum 30 day(P30) precipitations.It has been found that the multiple correlation coefficient of the equation involved Qs,>0.05 and Pss and P30 is the largest,and the contribution of Pss and P30 to ln Qs,>0.05 was estimated as 66.5% and 33.5%.A multiple regression equation between ln Qs,>0.05 and three influencing ariables(Pss,P30 and Atfgc) has been established,which indicates that the >0.05 mm sediment yield increased with Pss and P30,but decreased with Atfgc.Thus,the decrease in precipitation and sand-dust storms and the increase in the area of soil and water consrvation measures are the cause for the decreasing trend in the relatively coarse sediment yield.
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Received: 18 June 2007
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